Valve mechanism



Nov. 26, 1929. w. H. MANNING 1,737,316

VALVE MECHANISM Filed March 1, 1928 awe/nice Patented Nov 26, "1929WILLIAM H. MANNING, OF PONTIAC, MICHIGAN, ASSIGNOR TO GENERAL MOTORSCOR- PORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELAWARE VALVEMECHANISM Application filed March 1, 1928. Serial No. 258,282.

This invention relates to an internal combustion engine and moreparticularly to the valve actuating mechanism therefor.

In a poppet valve engine a certain clearance or lash must be allowedbetween the ends of the valve stems and the tappets or rocker arms, inorder to allow the valves to seat when the parts expand as the enginebecomes heated. This clearance, which usually approximates eight tofifteen one thousandths of an inch, is'objectionable because of thenoise it occasions while the engine is warming up and because it resultsin greater wear on the parts than would occur if a structure with noclearance were feasible.

It is one of the objects of the invention to avoid the necessity ofproviding valve stem clearance by providing an improved arrangementwhich will given Zero clearance throughoutthe entire range oftemperatures encountered in an internal combustion engine and which willprovide a quiet operating means for the valves.

Other objects and advantages of the invent-ion will appear in the courseof the following description, taken in connection with the accompanyingdrawing and appended claims.

In the drawing:

Figure 1 is an end view, partly broken away, of an internal .combustionengine embodying my invention.

Figure 2 is an enlarged plan .view of the valve operating mechanism,taken on the line 22 of Figure 1.

Figure 3 is a side elevationof the valve operating mechanism shown inFigure 2.

Figure 4 is a section on the line 44 of Figure 3.

Figure 5 is a side view, with parts broken away, of a portion of theengine illustrating the arrangement of the valves and intake and exhaustports.

The engine shown is of the conventional L-head type, the intake andexhaust valves 10 and 12 of which are normally held on their seats bythe springs 14 and 16 in the usual way. The push rods 18 and 20 arearranged to be actuated by cams 38 and 40 on the shaft 22 by means whichwill now be described.

Supported in the engine block on the outer side of the cam shaft 22 is ashaft 24 on which are independently journaled the hubs of rocker arms 26and 28. J ournaled on the shaft 24 between the rocker arm hubs is thehubof a T-arm 30 which comprises an arm carrying at its end a cross pin 32.Intermediate its end each of the arms ,26 and 28 is formed 011 its uppersurface with a slot 34 for receiving the adjacent end of pin 32.\Vashers 36 are fixed on shaft 24 on the outer sides of the rocker armhubs for holding the arms against lateral movement on the shaft.

The outer or free end of arm 28 rests on a cam 40 on the cam shaft. andlying on the surface of the outer end of arm 28 is a wedge 42. Rivetedto wedge 42 is a laminated spring 44. By reference to Figs. 2 and 4 itwill be noted that spring 44 is bifurcated on the end opposite the wedgefor embracing the arm 28 and extending beneath and beyond its hub, theintermediate portion of the spring resting on an end of cross pin 32..

On the side distant from the cam shaft, the hub of arm 28 is formed witha boss 46 with an opening for receiving a stud bolt 48. The b0lt'48extends between the furcations of the spring 44 and upon its lower endis threaded bolt 52 provided with flanges forengaging the sides of thespring. Vith this construction it is apparent that stud 48 maybeloosened to permit adjustment of spring 44 and wedge 42 toward and awayfrom push rod 20 for adjusting the clearance between the rod and wedge.

A spring 54 carrying a wedge 56 disposed under push rod 18 is fixed onrocker arm 26 in the same way that spring 44 and wedge 42 are fixed onthe arm 28.

The operation of the device will now be described. In setting the partsat ordinary temperatures, the studs 48 are loosened and springs 44 and54 are adjusted so that a zero clearance is provided between the uppersurfaces of wedges 42 and 56 and the lower ends of the correspondingpush rods 18 and 20. Studs 48 are then tightened. The springs 44 and 54are then in contact with pin 32. As the cam shaft rotates, the cam 40lifts the arm 28 to raise the push rod 20. As arm 28 lifts, it carrieswith it the T-arm 30 which also lifts the spring 54, thus withdrawingthe wedge 56 from its position between the free end of rocker arm 26 andthe lower end of push rod 18. The design of the apparatus, the length ofT-arm -30, the slope of the surfaces of the wedges, etc., are such thatwithdrawal of a wedge by operation of rocker arm 28, produces a clear--ance between the push rod and rocker arm greater than the maximumdecrease in distance between the end of the valve tappet 20 or, in casethe valve stem directly engages the wedge, between the end of the valvestem and the surface of the rocker arm upon which the wedge bottoms.This decrease in distance depends upon a number of factors among whichare the expansion of the valve stem and tappet and of the cylinderitself. \Vhen the rocker arm 28 resumes its lowered position, the pin 32moves downward and spring 54 pushes wedge 56 outward sufiiciently totake up the clearance between the rocker arm and the push rod, thestrength of spring 56 being insufficient to overcome the tension of thespring surrounding the valve stem and unseat the valve. Similar- 1y,spring Hand wedge 42 are operated to adjust the clearance between pushrod 20 and rocker arm 28 when arm 26 is rocked by the cam shaft.

\Vhen the engine is cold and is started running, the lifting of onerocker arm withdraws the other wedge and as the arm lowers, the force ofthe leaf spring causes the wedge to resume its original position. As theengine heats and the valve stems elongate,

the wedges are unable to return to their origi-.

nal position but are held slightly away from it, the leaf springs thenremain ng sl ghtly spaced from the upper side of pm 32 in the lowestposition of the latter.

\Vith the construction described, a condition of zero clearance for boththe intake and exhaust valves is maintained, regardless of thetemperatures existing. \Vhile I have illustrated a push rod interposedbetween each valve stem and the cam shaft, it 1s obvious that this isnot an essential feature, since the valve stem may extend directly tothe spacing wedge without the interposition of a push rod. Theexpression valve actuating member is used in the claims to denote amember which actuates a valve, whether the member is a valve stem, apush rod. a second rocker arm, or other element.-

The structure may be modified for adapting it to types of engines otherthan that illustrated, without departing from the scope of the inventionas defined in the appended claims.

I claim:

1. In an internal combustion engine. the combination of two valveactuating members, a pivotally supported rocker arm adjacent a pivotallysupported rocker arm adjacent each member and movable with itsrespective member, a leaf spring fixed to each arm and carrying a wedgeinterposed between the respective arm and member, means for rocking saidarms to actuate the members, and means actuated by rocking of one armfor withdrawing the wedge associated with the other arm.

3. In an internal combustion engine, the combination of two valveactuating members, a pivotally supported rocker arm adjacent each memberand movable with its respective member, a leaf spring fixed to each armand carrying a wedge interposed between the respective arm and member,means for rocking said arms to actuate the members, and a pivotallymounted arm carrying a cross pin extending between each rocker arm andits respective spring. 7

4. In an internal combustion engine, the combination of two reciprocablevalve actuating rods, a shaft adjacent thereto and carry ing rocker armspositioned to move with the respective rods, means for rocking saidarms, a leaf spring mounted on each arm and carrying a wedge positionedbetween the respective arm and rod, an arm rockably supported on saidshaft and carrying a pin extending between each rocker arm and itsspring.

5. In an internal combustion engine, including a reciprocable valveactuating rod, a rocker arm pivotally supported adjacent thereto andmovable with said rod, means for rocking said arm, a leaf spring fixedto said arm and carrying a wedge interposed between said arm and rod,and means operated by said engine for intermittently removing said wedgefrom its position between said arm and rod.

6. In an internal combustion engine, in

cluding a reciprocable valve actuating rod, a rocker arm pivotallysupported adjacent thereto and movable with said rod, means for rockingsaid arm, a spring pressed element supported on said rocker arm andmovable to vary the spacing between the rod and arm, and means operatedby said engine for intermittently moving said element to increase saidspacing. I

7. In an internal combustion engine, a pair of rocker arms,'a valveactuating member adjacent each rocker arm, a spring pressed elementsupported between each rocker arm and its respective valve actuatingmember and movable to vary the spacing therebetween, and means operatedby the movement of one rocker arm and its associated member for movingthe element associated with the other arm to increase the spacingbetween the other rocker arm and its associated member.

8. In an internal combustion engine including a spring pressed valveactuating element, a rocker arm operable with said ele- I ment, a wedgesupported on the rocker arm' and positioned between said arm and valveactuating element, and means operating automatically for intermittentlymoving said wedge in a direction to increase the clearance and returningit to a position to provide a zero clearance between said arm and valveactuating element.

9. In an internal combustion engine, a rocker arm and valve actuatingmember operable therewith, a wedge positioned between said elements forvarying the spacing therebetween, a leaf spring connected with saidwedge and rocker arm, and means for withdrawing said wedge.

10. Valve operating mechanism comprising, in combination with two valvesand means for alternately actuating each of said valves, spacingelements movable to a position to take up clearance between eachactuating means and its valve, means for resiliently moving said spacingelements to such position, and means actuated by theactuating means forone valve to move the spacing element for the other valve away from suchposition.

11. In a valve actuating mechanism a rocker arm, means forintermittently actuating said arm, a valve actuating member arranged tobe actuated by the movement of said arm, a leaf spring secured to saidarm and a wedge carried by said spring and positioned between said armand said valve actuating member.

In testimony whereof I aflix my signature.

WM. H. MANNING.

